The term Urtication can have various meanings:

• In biology, it refers to the stinging hairs of plants or insects, of which nettles (the plant genus Urtica) is the example from which the term was derived, but only one of a great many such plants. Many caterpillars have modified setae with associated venom glands, and these are called urticating hairs. A common example is the "saddleback caterpillar".

• In medicine, urtication, or flogging with nettles, is the process of deliberately applying stinging nettles to the skin in order to provoke inflammation or rash. An agent thus used is known as a rubefacient (i.e. something that causes redness). This is done as a folk remedy for rheumatism, as it provides temporary relief from pain.

• Urtication is also performed by BDSM practitioners who use stinging nettles for sexual stimulation.

BDSM | Entomology